Correct Answer : Get Lastest Questions and Answer : Explanation: : To process the data, Job Tracker assigns certain tasks to the Task Tracker. Let us think that, while the processing is going on one DataNode in the cluster is down. Now, NameNode should know that the certain DataNode is down , otherwise it cannot continue processing by using replicas. To make NameNode aware of the status (active / inactive) of DataNodes, each DataNode sends a "Heart Beat Signal" for every 10 minutes (Default). This mechanism is called as HEART BEAT MECHANISM Based on this Heart Beat Signal Job Tracker assigns tasks to the Tasks Trackers which are active. If any task tracker is not able to send the signal in the span of 10 mins, Job Tracker treats it as inactive, and checks for the ideal one to assign the task. If there are no ideal Task Trackers, Job Tracker should wait until any Task Tracker becomes ideal. When TaskTrackers send HeartBeats back to JobTracker , it also include other information like Status, Counters, and Data Read/Write status.
Question : Select statements, which are correct with respect to Spark Streaming
1. You can use other language program in MapReduce
2. It May Increase or decrease the performance of Job
1. Writable data types are specifically optimized for network transmissions 2. Writable data types are specifically optimized for file system storage 3. Access Mostly Uused Products by 50000+ Subscribers 4. Writable data types are specifically optimized for data retrieval
1. Hadoop API will convert the data to the type that is needed by the reducer. 2. Data input/output inconsistency cannot occur. A preliminary validation check is executed prior to the full execution of the job to ensure there is consistency. 3. Access Mostly Uused Products by 50000+ Subscribers 4. A real-time exception will be thrown and map-reduce job will fail
1. Yes, there is a special data type that will suppress job output 2. No, map reduce job will always generate output. 3. Access Mostly Uused Products by 50000+ Subscribers 4. Yes, but only during map execution when reducers have been set to zero